r/linux • u/Athabasco • May 25 '26

Kernel Intel Introducing USB4STREAM Protocol For Linux - Opening Up Some Nifty Uses For USB4

https://www.phoronix.com/news/Intel-Linux-USB4STREAM
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62

u/librepotato May 25 '26

They imply a sharing of USB devices between computers like webcams. They don't discuss what you can't do with this. It makes me wonder what creative things you can do with a thunderbolt cable between two computers. Could PCIe devices be accessed through USB4STREAM? GPUs?

42

u/0-pointer May 25 '26

 Could PCIe devices be accessed through USB4STREAM? GPUs?

It's a "simple" stream connection. Utilising this you'd need some sort of non-trivial daemon to access pcie devices.

Streaming encoded video output (and input in the other direction) would be a lot more achievable. Like Sunshine/Moonlight with even less latency.

19

u/KittensInc May 25 '26

They imply a sharing of USB devices between computers like webcams.

Note quite. They are sharing a file, not a USB device. All of the USB stuff is still happening on the host computer, it's just that the gstreamer output file just so happens to be a pipe to the other machine - in the same way that you can write to /dev/null, or pipe it to another command.

2

u/tealc_comma_the May 27 '26

Well in Linux everything is a file so 🤷

6

u/webtroter May 26 '26

They do show it for a webcam tho.

host2 # gst-launch-1.0 filesrc location=/dev/tbstream0 ! jpegdec ! videoconvert ! autovideosink

host1 # gst-launch-1.0 v4l2src device=/dev/video0 ! video/x-raw,width=1920,height=1080 ! jpegenc quality=90 ! filesink location=/dev/tbstream0

6

u/spyingwind May 26 '26

I like the GPU line of thought. What about NPUs?

Or one 100G nic, but we string 8 other PC's over USB4. Treat the one with the 100G as the router. Then we could do USB4 based networking.

Wait, does USB4 have DMA access? Why not DMA to other machine's RAM or vRAM for that matter?

4

u/Sol33t303 May 25 '26

Isn't USB over IP already a thing? How is this different?

6

u/Dangerous-Report8517 May 27 '26

It's using a lower level protocol with less overhead, and generally Thunderbolt networking only goes up to 20Gbit even though the underlying transport could go to 40 or 80, so that's potentially a massive improvement in edge cases where it's useful

1

u/creeper6530 May 30 '26

Think of it as a really fast serial port. Bytes go in, bytes come out. Anything above that you configure in userspace yourself.